Omer Khayam

Infinera (United States)

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H. Benisty

Laboratoire Charles Fabry

Fred Kish

North Carolina State University

M. Missey

Infinera (United States)

Jiaming Zhang

Peng Cheng Laboratory

A.G. Dentai

Infinera (United States)

Huan-Shang Tsai

Infinera (United States)

Jeffrey Rahn

Meta (United States)

T. Butrie

Infinera (United States)

Mike Reffle

Infinera (United States)

M. Küntz

Robert Bosch (Germany)

Cooperative Institutions

Infinera (United States)

Institute of Electrical and Electronics Engineers

Nokia (United States)

University of California, Santa Barbara

Centre National de la Recherche Scientifique

Infineon Technologies (Canada)

University of Illinois Urbana-Champaign

Alcatel Lucent (Germany)

JDSU (United States)

Karlsruhe Institute of Technology

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Constellation shaping for high symbol rate SNR limited transceivers

Robert Maher Mehdi Torbatian S. Koenig Omer Khayam A. Le Liepvre

The information rate (IR) of a digital coherent transceiver is constrained by the inherent practical signal-to-noise ratio (SNR) limit. Coded modulation, which is the combination of multi-level modulation and forward error correction, aims to maximize the IR within this SNR envelope. While probabilistic constellation shaping has enhanced this methodology by providing an increase in IR over conventionally employed square quadrature amplitude modulation (QAM) formats, it is the ability to eloquently tune the per wavelength IR by varying the symbol probabilities that has gained this scheme significant traction within optical communications in recent years. As commercial line cards continue their evolution towards 100 GBd and to modulation formats beyond 64QAM, we discuss the merits of probabilistic shaping for high symbol rate digital coherent transceivers in the presence of a practical SNR limit.

Symbol rate

Modulation (music)

QAM

Transceiver

Constellation diagram

10.1117/12.2509151

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Citations (4)

General recipe for flatbands in photonic crystal waveguides

Optics Express (2009)

Omer Khayam H. Benisty

We present a general recipe for tailoring flat dispersion curves in photonic crystal waveguides.Our approach is based on the critical coupling criterion that equates the coupling strength of guided modes with their frequency spacing and results in a significant number of the modes lying collectively in the slow-light regime.We first describe the critical coupling scheme in photonic crystal waveguides using a simple coupled mode theory model.We also determine that canonical photonic crystal waveguides natively correspond to strongly coupled modes.Based on these analyses, our design recipe is as follows: Tune the profile of the first Fourier component of the waveguide periodic dielectric boundary to lower the coupling strength of the guided modes down to its critical value.We check that this generalized tuning may be accomplished by adjusting any desired optogeometric parameter such as hole size, position, index etc.We explore the validity of this general approach down to the narrow two-missing rows waveguides.The interest of this method is to circumvent most of the common trial-and-error procedures for flatband engineering.

Waveguide

Coupled mode theory

10.1364/oe.17.014634

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Citations (37)

Large-scale Monolithic Integration Enabling Terabit Transmitters and Receiver Chips in a Coherent Super-channel Architecture

Advanced Photonics Congress (2012)

Masaki Kato Damien Lambert V. Lal M. Küntz Joseph A. Summers

In this talk, we review InP-based, 10 wavelength, polarization-multiplexed quadrature phase-shift keying (PM-QPSK) transmitter and receiver photonic integrated circuits (PICs) that enable terabit coherent super-channel architecture.

Terabit

Amplitude-shift keying

10.1364/iprsn.2012.im2a.4

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Citations (2)

Dark modes: a periodic multimode waveguide perspective

HAL (Le Centre pour la Communication Scientifique Directe) (2010)

H. Benisty Omer Khayam

Waveguide

Source

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Spontaneous Emission and Coupled-Mode Theory in Multimode 1-D Systems With Contradirectional Coupling

IEEE Journal of Quantum Electronics (2011)

H. Benisty Omer Khayam

By means of source terms and coupled-mode theory, the essential features of spontaneous emission in multimode waveguides with counterdirectional feedback, such as corrugated and photonic crystal waveguides, are described in a heuristic manner. These multimode source terms generalize a similar approach evoked in multilayer structures. We account for features such as the “mini-stopband,” and the “stripe of minigaps” of broad photonic crystal waveguides, modeling previous experimental data. The result holds in several situations for which the differences in source terms for the uncoupled waveguide modes are not important. The approach yields significant results through a simple path.

Waveguide

Amplified spontaneous emission

Stopband

Coupled mode theory

Mode (computer interface)

10.1109/jqe.2010.2076335

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Citations (6)

DOS Modulation and Slow Light in Broad Photonic Crystal Waveguides

HAL (Le Centre pour la Communication Scientifique Directe) (2009)

Omer Khayam H. Benisty

Modulation (music)

Slow Light

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Littrow resonators and the critical coupling concept

H. Benisty Omer Khayam

We describe a class of open resonators formed by highly corrugated broad waveguides. The contra-directional coupling induced by the corrugation can be seen as a Littrow diffraction event on a reflection grating. The presence of both boundaries still discretizes the modes. The modes most affected by this Littrow diffractions are the higher order modes of the broad waveguide. The new modes that emerge from their coupling may have collectively a low group velocity in a sizable part of the Brillouin zone. For this, a critical coupling value has to be found, minimizing the minibands and maximizing the "stripes of minigaps" between them. We give various implementations of this geometry, including an analogy with graphene nanoribbons. Furthermore, the analysis of the emerging field pattern of a toy-model shows phenomena previously identified in light localization studies, with large frequency intervals of "smooth" behaviour at "stripes of minigaps", separated by narrow frequency intervals of quickly evolving patterns.

Brillouin zone

Reflection

Waveguide

10.1109/icton.2010.5549060

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Citations (2)

Functional control from broad waveguides, photonic crystal and "Littrow mode" approaches

HAL (Le Centre pour la Communication Scientifique Directe) (2009)

H. Benisty Omer Khayam Cyril Cambournac

Mode (computer interface)

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Broad Periodic Waveguides : Simultaneous Slow Light of Multiple Modes

AIP conference proceedings (2009)

H. Benisty Omer Khayam Dmitry N. Chigrin

A periodic multimode waveguide provides contradirectional feedback of all its modes. The relative constancy of feedback strength results in regular bands and stripes of minigaps at zone edges. A critical coupling strength was recently shown to flatten the bands and provide collective slow light. We connect these aspects to the “Littrow lasing” geometry and to spontaneous emission modification on the application side or to “dark modes” on the theoretical side.

Slow Light

Waveguide

Coupling strength

10.1063/1.3253932

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Sharp resonance of multimode periodic waveguide open resonator defined in SOI

HAL (Le Centre pour la Communication Scientifique Directe) (2010)

N. Piskunov H. Benisty Omer Khayam

Waveguide

Q factor

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Citations (1)